AI agents call youtube_list_subscriptions to retrieve information from Youtube without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves subscription data for the authenticated user. While it is a Read operation, the severity is elevated to medium because: (1) it reveals personal subscription preferences and habits, which constitutes sensitive personal data disclosure; (2) in the context of an MCP server with full YouTube channel control, unauthorized subscription enumeration could enable targeting or profiling of the channel…
From the tool's definition Tool description states it "List[s] all channels that the authenticated user is subscribed to" using the subscriptions.list endpoint. This is a retrieval operation with no modification or side effects.
Attacks that exploit this kind of access
List all channels that the authenticated user is subscribed to, using the YouTube Data API v3 subscriptions.list endpoint with mine:true. Args: - \. It is categorised as a Read tool in the Youtube MCP Server, which means it retrieves data without modifying state.
Register the Youtube MCP server in PolicyLayer and add a rule for youtube_list_subscriptions: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Youtube. Nothing to install.
youtube_list_subscriptions is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the youtube_list_subscriptions rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for youtube_list_subscriptions. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
youtube_list_subscriptions is provided by the Youtube MCP server (tuitamogamer-gpt/youtube-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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